The Induction Electromotive force type velocity detector (IEVD) can directly detect velocity with high resolution, without contact on an object.

In this paper, we research the induction electromotive force, signal -to-noise ratio of the two-coil sensor, all of these can lay the foundation for designing apparatus.

Using the slider to drive a metal bar to cut perpendicularly the uniform magnetic field in the center of a Helmholtz coil, induction electromotive force could be produced.